This invention relates generally to hand-operated siphons of the type adapted to enable transfer of liquids from one vessel to another.
In the past, a number of different siphon constructions have been proposed and produced, and have met with varying degrees of success. Prior siphons have incorporated cylinders carrying reciprocatable pistons which were operated by handles that were disposed outside the cylinder body. In most cases, the plunger functioned merely to permit initial evacuation of a portion of the cylinder so as to cause the fluid that was being siphoned to be drawn into the cylinder, for starting up the siphoning action. Several prior siphons incorporated sufficient room at the top of the cylinder such that the piston could be driven past the outlet line to a storage position which was out of the path of flow of the liquid being siphoned.
While the above constructions were satisfactory in some respects, a number of distinct disadvantages became apparent to the user when he attempted to put these devices into operation. In cases where the inlet hose was connected to the bottom of the cylinder, and in instances where the length of the inlet hose was appreciable, very often it was not possible to initiate the necessary siphoning action. This occurred mainly in siphon constructions employing a relatively small diameter cylinder, and resulted from the fact that the displacement of the piston in the cylinder was less than the volume of air occupying the inlet hose. Under such cirmumstances, even with a complete withdrawal of the plunger and piston, the resulting evacuation of the cylinder was insufficient to cause an adequate quantity of liquid to reach the outlet line such that siphoning action could begin. With such devices, the only solution was to either shorten the inlet hose considerably, so as to minimize the trapped air in the system, or to manually prime the siphon by filling the inlet hose with liquid, thus getting rid of the trapped air and permitting the start of the siphon action after the plunger was initially withdrawn.
Other disadvantages became apparent with most of the prior art devices, where the difference in level between the supply-vessel and the bottom of the outlet hose was small. In such cases, the resulting pressure was often insufficient to support a reasonably good flow rate. The only solution to this problem was to increase the height of the supply-vessel, or alternately to employ a siphon arrangement incorporating larger diameter cylinders and corresponding hosing of increased size. However, frequently there were restrictions as to the maximum size siphon that could be used, due to space limitations such as commonly encountered in the marine facilities, or transportation vehicles, etc., with which these devices were typically employed. In addition, physically large components were considered too cumbersome to store because of their bulkiness, and in many cases not appealing to the consumer, whether he be an individual or an industrial concern.
Of course, in cases where there existed no difference in levels between the supply tank and the receiving tank, siphoning was not possible at all. A separate, manual pump was then required.